Conducting and evaluating rangeland monitoring data is critical to understand the influence of management practices on Sandhills plant communities and soil health. A network of knowledge exchange between cattle producers and scientists can help this data become more meaningful and useful in an adaptive rangeland management framework.
The SRMC Project
The SRMC is a collaborative project between UNL Extension, USDA-NRCS, and cattle producers in the Sandhills of Nebraska. The SRMC project aims to conduct and evaluate monitoring data on a growing number of ranches in the Nebraska Sandhills, connecting ranchers, scientists, and the public in a network of ongoing knowledge exchange relating to rangeland health and management.
How Monitoring is conducted on Cooperative Ranches:
At each ranch, 3 to 4 pastures were selected to represent their typical management. Within each pasture, we selected 3 study sites at least 0.25 miles from water where possible. All study sites were located on upland Sands ecological sites. Data collected and presented here represent only uplands, dune tops, and slopes. Lowlands and wet meadows are important components of the Nebraska sandhills ecosystem but were omitted for consistency so that sites could be compared. Efforts were made to place these sites on different topographic positions (i.e., north-facing slope, south-facing slope, and dune top) to include the potential variability in the pastures. At each site, we recorded the GPS location as a middle point and then we took a photo point in three different directions (north, southwest, southeast), one pace away from the middle point. At every pace (two steps) a frame was placed and the vegetation was monitored for 11 paces/readings. A total of 99 frames were measured for each pasture.
Monitoring Methods Used
Photo points are used as a quick and easy monitoring tool to document management practices of a ranch. Although photographs cannot depict all details about an area, they can provide good information about a specific location over a number of years. Photo points can be used for baseline monitoring, indicating “normal” conditions, or be used to monitor trends or changes in that location. They can be looked back on to provide insight on problem areas, or document implications of specific management practices.
Percent cover is an important rangeland indicator that can withstand differences in seasonal and yearly precipitation and utilization. When bare ground is prevalent or increases over the years it indicates a risk of erosion. We quantified ground cover by identifying what was directly underneath the tip of the cover point (a wood screw) located on the monitoring frame. We identified what we saw as litter, bare ground, or basal live vegetation. If we hit basal live vegetation, we recorded the species. From these observations, we calculated percent cover.
Frequency of Occurrence
Frequency of occurrence is used to evaluate trends and changes in rangeland vegetation. It highlights the most commonly observed species across the site. Upon placing frame on the ground, we listed all species present within the 40 cm frame.
Dry Weight Rank (DWR)
To look at species composition in terms of production by dry weight, we used the dry weight rank estimating procedure. Dry weight rank can be used to compare production and species composition across sites and to highlight the most productive species in the area. Samplers rank the top three species by visually estimating the 1st, 2nd, and 3rd most productive species by dry weight in the 40cm frame.
To look at soil health measures, we collected 2 soil cores 0 to 8 inches deep at the middle and end of each transect on plant interspaces (6 cores per study site). We then combined cores from a single study site in a clean bucket and placed samples into soil sample bag to be sent to a lab for analysis.
Calculating forage production is a monitoring method that helps with determining the carrying capacity of your ranch or pastures. Clipping areas for vegetation production can help develop mental (or photo) references for visually monitoring range conditions. Vegetation production was determined by placing 5 grazing exlosure cages (fig. 23) in pastures before grazing occurred. We hand clipped all the vegetation within a 1/4 meter frame and sorted it into 7 functional groups (see fig. 24): warm season grass, cool season grass, annual grass, sedge, forb, cactus, standing dead vegetation, and litter.
Elevation and GPS locations for each study site were collected from a Garmin GPS Unit. Aspect and slope data was collected from a USGS Digital Elevation Model (DEM) in the spatial analysis program ArcGIS.
Current (2019) and long term (1981-2010) precipitation and temperature data was taken from the PRISM Climate Group. This data incorporates modeling done by PRISM and even with advanced quality control in place, it may not always match the records taken directly from the ranch.
Ecological Sites are NRCS land classifications for areas that respond similarly to management practices and disturbance. Classification is based on climate, soil, geology, hydrology, and vegetation. Ecological sites can be visualized using The Ecosystem Dynamics Interpretive Tool (EDIT). EDIT is managed by USDA Natural Resources Conservation Service, the USDA Agricultural Research Service (ARS) Jornada Experimental Range and New Mexico State University (NMSU).
Gudmundsen Sandhills Laboratory (GSL) Monitoring Results
What is GSL?
The Gudmundsen Sandhills Laboratory, or GSL, is located in the central Sandhills of Nebraska and is one of our SRMC ranches. It was gifted to the University of Nebraska Foundation by "Pete" and Abbie Gudmundsen. The University of Nebraska-Lincoln leases the land from the Foundation in order to establish and maintain this research oriented ranch and facility. The multidisciplinary projects based at GSL have resulted in increased understanding of the Sandhill's ecosystem and led to advances in livestock and rangeland management topics. Research faculty involved in these projects are affiliated with the West Central and Panhandle Research Education and Extension Centers, several other departments, and the School of Natural Resources on campus in Lincoln. The GSL cowherd consists of approximately 350 March-calving, 100 June-calving and 60 August-calving cows. Forage resources include 1,200 acres of subirrigated and wetland meadows along with 11,600 acres of upland sandhills range which includes sands, sandy and choppy sands ecological sites. Stocking rates for upland and subirrigated meadow are 0.5 and 3.5 AUM's/acre, respectively (UNL Extension).
Map of GSL Monitoring Study Sites
GSL Climate Data
2019 & 2020 Vegetation Cover on Upland Dunes and Slopes at GSL
In the graph below, litter makes up 60-81% of uplands cover in each pasture, differing slightly by year. This amount of litter is beneficial to overall pasture health, acting as a protective mulch for live native plants. Bare ground is less than 21% of the upland cover in each pasture, indicating that erosion is currently not an issue. Basal live vegetation, or rooted plants, made up 12-19% of the percent cover on the uplands of the study pastures over the two years.
2019 & 2020 Frequency of Occurrence on Upland Dunes and Slopes at GSL
The graphs below shows the plant species we would most frequently see when placing frames across the uplands of the study pastures. Results indicate that our biggest players in terms of species frequency on upland sites would be stiff sunflower, sedges, little bluestem, sedge, and rosette grasses.
2019 & 2020 Dry Weight Rank (DWR) on Upland Dunes and Slopes at GSL
The graphs below highlight the most productive species on the upland dunes and slopes in monitored pastures at GSL in 2019 and 2020. Here we see stiff sunflower, little bluestem, needle grasses, and switchgrass were the big players in terms of production.
Infrequent Plants on Upland Dunes and Slopes on GSL study pastures
Below is a list of plants found in the study pastures that had <5% frequency of occurrence or <1% dry weight rank in our 2019 monitoring on upland dunes and slopes at GSL.
Making Sense of GSL Monitoring Data
There are a number of ways you can interpret and use monitoring data, whether you have a single year or many years of data. One way is to compare collected data to the NRCS state and transition models for the ecological site you are monitoring.
Using NRCS State-and-Transition Models to Interpret Monitoring Data
The diagram below displays a general outline and model of the dominant plant communities as defined by USDA NRCS for the Sands Medium P.Z. ecological site. It indicates pathways that lead to transitions to other plant communities based on management actions. Although this model may not represent the exact target plant community for your ranch’s pastures, it can be a useful reference for continued monitoring on your ranch for changes in plant communities in response to management. Our 2019 data suggests that the dominant plant communities at our GSL study sites are similar to the target with little bluestem, sand bluestem, and needlegrass as important species in both frequency of occurrence and dry-weight rank. Fall and scribners rosette grasses, sand dropseed, sedges and stiff sunflower were also important species within the study. A notable departure from the State-and-Transition model was prairie sandreed, which was typically observed in 30 to 40% of frames but not a large producer in dry weight rank.
A “Similarity Index” can help us understand the extent and direction of changes that have taken place on a site from its reference plant community. We can then begin to predict changes from new grazing management strategies or other practices. Evaluating your similarity index provides a baseline of information which helps establish goals and objectives for rangeland management. Changes in similarity index can be monitored over time to help determine if you are meeting management goals. If vigorous, productive, palatable plants are present on a particular ecological site, then the similarity index score will be higher, and that rangeland is considered to be in a higher state of health. If weedy, poor producing, unpalatable plants dominate this same range site, then a the similarity index score will be lower, and that rangeland is considered to be in a lower state of health.